In recent years, due to advances in electronic technology, mobile electronic devices such as mobile telephones, notebook personal computers, audio/visual devices, camcorders, or personal digital assistants are rapidly becoming popular. These electronic devices are typically systems driven by secondary batteries and in order to extend the time of operation, conventional sealed lead storage batteries as well as Nickel-cadmium batteries, nickel Metal hydride batteries and also the new type of high energy dense secondary batteries such as lithium ion (Li ion) secondary batteries are usually loaded in these devices. As a result, advances are being made in making the mobile electronic devices lighter and more compact and thus higher functionality of the mobile electronic devices can be achieved. For the lithium ion secondary batteries in particular, the energy density is higher and thus advances are being made in the quality battery of activity and in high capacity battery structures. Also, much effort is being made to realize a battery power source with longer usage time for a single charging. As a result, capacity which is a number of times higher that than of the secondary batteries of the prior art in terms of capacity ratio has been realized.
However, the secondary batteries must be charged after a fixed amount of power is used, and because charging equipment and a comparatively long charging time is required, if a mobile electronic device is be used continuously over a long period without limits of time and location, it must be used while being charged.
A known use for a mobile electronic device is that in which a mobile information terminal device (called a mobile type information terminal) is distributed to visitors to a public facility such as a gallery or museum in order to provide information on the objects being displayed (see Japanese Patent Laid-Open 2002-259612: paragraphs 0011-0029 and FIGS. 1-9, for example). According to this technology, there is transmission between the mobile type information terminal held by the visitor and the exhibit, and information such as text, image and sound pertaining to the description of the exhibit can be displayed or generated. In the mobile type information terminal utilized for this purpose, it is particularly necessary for the mobile type information terminal to be used while sufficiently ensuring battery capacity for the secondary batteries. For this reason, a fuel cell is loaded in the mobile type information terminal along with the secondary batteries, and the battery capacity for the secondary cell is ensured by running the device while charging the secondary cell with the fuel cell (see Japanese Patent Laid-Open 2004-227832: paragraphs 0014-0043 and FIGS. 1-7, for example).
Known examples of the fuel cell include one in which liquid fuel is oxidized in a MEA (Membrane Electrode Assembly) anode including anode, an electrolytic film, a cathode and a dispersion layer, and oxygen is reduced by the cathode, and in the technology of Patent Document 2, the direct methanol fuel cell (DMFC) is used as a typical fuel cell.
When a fuel cell is used in this manner, in order to prevent characteristic deterioration of the fuel cell, the secondary cell is appropriately charged while self diagnosis of the charge circuits including the fuel cell is performed. For example, technology is disclosed in which the resistance value for membrane resistance is obtained based on the voltage generated for the membrane resistance of the fuel cell and the resistance value of the reaction resistance is obtained based on the current value which is supplied for reaction resistance and the voltage value generated for reaction resistance. The effective resistance of the fuel cell is then efficiently obtained in a short time from the membrane resistance and the reaction resistance previously obtained, and self diagnosis to determine whether the fuel cell is undergoing characteristic deterioration is performed (see Japanese Patent Laid-Open 2003-223918: Claim 1 and FIG. 1, for example).
Known examples of the fuel cell include one in which liquid fuel is oxidized by a MEA (membrane electrode assembly) anode including an anode, an electrolytic film, a cathode and a dispersion layer, and oxygen is reduced by the cathode, and in the technology of Patent Document 2, the direct methanol fuel cell (DMFC) is used as a typical fuel cell. In addition, technology is known in which the secondary battery and the DMFC are loaded in a mobile telephone and the capacity of the secondary battery is ensured by charging the secondary battery from the DMFC as necessary (See Japanese Patent Laid-Open 2004-1944434, Claim 1 and FIG. 1 for example).